The Environment Agency has started a critical round of water quality testing around England’s coastline.
More than 400 beaches and inland bathing sites are tested every week between May and September.
Strict new European standards come into force next year, with 40 sites currently at risk of failure. This would mean local authorities being forced to display a sign advising against swimming at these popular places.
Pollution remains at some swimming sites in England due to agriculture, sewage overflows, animal and bird faeces and badly connected drainage.
Paul Hickey, deputy director of water quality at the EA, said: “The seaside economy in England is worth around £3.6bn each year – and every improvement in bathing water quality helps to protect that.
“With one year to go until the new EU standards come into effect, the EA and partner organisations are focusing efforts on the small number of problem sites to bring them up to standard.”